Solid ring needle roller bearings have a smaller volume and higher load-bearing capacity. Therefore, this type of bearing can meet the requirements of light weight, small space occupation, and high power transmission. Depending on the application, bearings with or without inner rings can be used. The outer ring has double retaining edges (or double locking rings) with cage needle bearings NA and NKI types.

The inner and outer rings (with lock ring, complete set of needle rollers, and cage) can be installed separately, with high permission speed and can be divided into single and double rows. If the shaft cannot be used as a raceway, that is, if it is impossible or uneconomical to harden the shaft and grind it, then such needle roller bearings with inner rings can be used.

NA and NKI type bearings without inner rings are RNA and NK type needle roller bearings.

This type of bearing has no inner ring and is suitable for supporting structures with limited radial installation size. The journal that matches the bearing directly serves as the rolling surface. As the shaft of the raceway surface, it must be hardened and ground, and only when it is processed to the appropriate size and shape accuracy can the complete set of needle roller bearings have a higher lifespan and operating accuracy. Meanwhile, due to the absence of inner rings, the diameter of the shaft can also be appropriately increased, thereby increasing rigidity.

Single or double-sided sealed needle roller bearings can effectively prevent the invasion of dirt, and the bearings are filled with an appropriate amount of lithium based grease. The inner ring of this type of bearing is wider than the outer ring, which ensures good sealing and prevents contamination of the shaft when there is a slight displacement of the bearing relative to the bearing box. The inner ring of the bearing also has lubricating oil holes, which can be supplemented with lubrication by the outer or inner ring according to the configuration needs.